git.m6w6.name Git - m6w6/libmemcached/blob - testing/lib/ForkAndExec.cpp

   1 #include "ForkAndExec.hpp"
   2
   3 #include <cerrno>
   4 #include <cstdio>
   5
   6 #include <fcntl.h>
   7 #include <sys/poll.h>
   8 #include <unistd.h>
   9
  10 ForkAndExec::ForkAndExec(const char *binary_, char **argv_)
  11 : ready{-1, -1}
  12 , pipes{-1, -1}
  13 , binary{binary_}
  14 , argv{argv_}
  15 {
  16 }
  17
  18 ForkAndExec::~ForkAndExec() {
  19   for (auto &pipe : {ready, pipes}) {
  20     for (auto m : {READ, WRITE}) {
  21       closePipe(pipe[m]);
  22     }
  23   }
  24 }
  25
  26 int ForkAndExec::createPipe() {
  27   if (pipes[mode::READ] == -1) {
  28     if(pipe2(pipes, O_NONBLOCK)) {
  29       perror("ForkAndExec pipe()");
  30       return -1;
  31     }
  32   }
  33
  34   return pipes[mode::READ];
  35 }
  36
  37 pid_t ForkAndExec::operator()()  {
  38   if (!prepareExecReadyPipe()) {
  39     return 0;
  40   }
  41
  42   switch (pid_t pid = fork()) {
  43     case 0:
  44       closePipe(pipes[mode::READ]);
  45       prepareOutputPipe();
  46       execvp(binary, argv);
  47       perror("ForkAndExec exec()");
  48       _exit(EXIT_FAILURE);
  49
  50     case -1:
  51       perror("ForkAndExec fork()");
  52       return 0;
  53
  54     default:
  55       pipes[mode::READ] = -1;
  56       closePipe(pipes[mode::WRITE]);
  57       pollExecReadyPipe();
  58       return pid;
  59   }
  60 }
  61
  62 bool ForkAndExec::prepareExecReadyPipe() {
  63   if (ready[mode::READ] == -1) {
  64     if (pipe2(ready, O_CLOEXEC | O_NONBLOCK)) {
  65       perror("ForkAndExec pipe()");
  66       return false;
  67     }
  68     closePipe(ready[mode::WRITE]);
  69   }
  70
  71   return true;
  72 }
  73
  74 void ForkAndExec::prepareOutputPipe() {
  75   if (pipes[mode::WRITE] != -1) {
  76     if (0 > dup2(pipes[mode::WRITE], STDERR_FILENO) ||
  77         0 > dup2(pipes[mode::WRITE], STDOUT_FILENO)) {
  78       perror("ForkAndExec dup()");
  79     }
  80   }
  81 }
  82
  83 void ForkAndExec::closePipe(int &fd) {
  84   if (fd != -1) {
  85     close(fd);
  86     fd = -1;
  87   }
  88 }
  89
  90 void ForkAndExec::pollExecReadyPipe() {
  91   pollfd fd{ready[mode::READ], 0, 0};
  92   if (1 > poll(&fd, 1, 5000)) {
  93     cerr << "exec() timed out" << endl;
  94   }
  95 }